The invention relates to a control arrangement, in particular a power-control arrangement for a vehicle engine, having a movable actuating lever, particular a pedal, and a damping device which counteracts movement of the actuating lever. In order to give the operator of such a control arrangement a perceptible indication of force along the displacement of the actuation lever for example, a gas pedal) and to avoid excessive vibration of the arrangement, damping, e.g. by frictional elements, is also provided in addition to a restoring force--usually displayed by a restoring spring. Naturally, such damping is usually the same in both directions of movement, that is to say counter to the restoring force as well. On account of aging, wear or the like, the damping can become excessive, with the result that the control arrangement is only restored slowly or, in the extreme case, not at all.
A damping or braking hysteresis has therefore already been provided between the two directions of movement. One embodiment is described in DE 34 12 318 A1. In this document, frictional elements which can be moved in a translatory manner are subjected to the action of a restoring spring. When the pedal is pressed down, they are pressed against their mating frictional surfaces increasingly the more the spring is stressed, whereas when the movement is reversed the contact-pressure force, and thus the action of friction, are reduced as relaxation of the spring increases. With this arrangement, however, it would be possible for the pairs of frictional elements to wedge against one another as spring force increases.
In another known method of frictional damping for a gas pedal (DE 195 17 172 A1), the pedal-restoring spring is arranged between the pedal itself and a rocker-type braking lever. The latter presses a friction lining onto a rotary bearing sleeve of the pedal lever. The contact-pressure force of the friction lining increases proportionally as the pedal is pressed down further, and decreases correspondingly again when the pedal is released. At the moment the pedal is released (turning point), however, the maximum friction force is still effective temporarily.
In one relevant arrangement with hydraulic displacement transmission (DE 25 50 326 A1) from a pedal-side master cylinder to a control-side slave cylinder, there is a stronger restoring spring on the slave cylinder than on the master cylinder, with the result that the slave cylinder cannot trail when the pedal is relieved of loading. Damping of this arrangement is ensured by the unavoidable flow resistances between the master and slave cylinders; on the other hand, there is no force hysteresis between the pedal being loaded and relieved of loading.